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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: Câu 21. Thực hiện phép tính: 8.( -1 2 )^ 4 2/3 + – 1/3 + 7/15 (0,8.7+0,64).(1,25.7- 4 5 .1,25)+31,64

Toán Lớp 7: Câu 21. Thực hiện phép tính:
8.( -1 2 )^ 4
2/3 + – 1/3 + 7/15
(0,8.7+0,64).(1,25.7- 4 5 .1,25)+31,64

Comments ( 1 )

  1. a) 8 × ( -1/2 )^4
    = 8 × 1/16
    = 1/2
    b) 2/3 + (-1)/3 + 7/15
    = 1/3 + 7/15
    = 4/5
    c) ( 0,8 × 7 + 0,64 ) × ( 1,25 × 7 – 4,5 × 1,25 ) + 31,64
    = ( 28/5 + 0,64 ) × [ 1,25 × ( 7 – 4,5 ) ] + 31,64
    = 156/25 × [ 1,25 × 5/2 ] + 31,64
    = 156/25 × 25/8 + 31,64
    = 39/2 + 31,64
    = 2557/50
    @Rin

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222-9+11+12:2*14+14 = ? ( )

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